Study On The Application Of Best Ethanol Fermentation Strain

With the increasing demand for ethanol,alcohol fermentation industry will increase the production efficiency and reduce the cost of production.Saccharomyces cerevisiae is a common strain in ethanol fermentation.The performance of S.cerevisiae plays an important role in ethanol fermentation.An excellent S.cerevisiae strain can greatly improve the ethanol fermentation yield.The very high gravity fermentation is a promising technology,which can improve the comprehensive benefit of alcohol plant and optimize the conditions of alcohol fermentation,which is beneficial to the increase of ethanol production.The improved active dry yeast fermentation technology can improve the yield of active dry yeast,and obtain higher quality active dry yeast products,and promote the improvement of product quality and the extensive application of yeast.Therefore,this paper will focus on the above aspects of research,in order to improve the level of ethanol fermentation.Fermentation process first on Maize culture medium was determined,by comparing the ethanol fermentation residual sugar content,the end point of ethanol fermentation was 72 h,at this time the residual sugar content reached below 2%and there is no obvious follow-up change.17 strains of S.cerevisiae in our laboratory were used in the very high gravity fermentation of ethanol,and the residual sugar content was tracking and ethanol yield was determined at the end of ethanol fermentation.The results showed that the fermentation performance four strains H1,H3,H7 and H17 was better than those of the other 13 fermentation samples.Therefore,these four strains was selected and used in the next experiment.The conditions of ethanol fermentation were optimized by changing the glucose content,ethanol content,the amount of yeast strain in the fermentation broth and the initial sugar concentration in the liquid culture medium of YPD.The content of residual reducing sugar and ethanol production in fermentation broth at the.end of fermentation were determined,and the difference between them was analyzed.The results showed that the optimal conditions of ethanol fermentation was:adding 0%glucose liquid YPD yeast culture medium,adding 6%ethanol,the amount of inoculation in the fermentation broth of 1*108 cfu/mL,initial glucose concentration in fermentation medium was 220 g/L.In the preparation of active dry yeast,the centrifugal conditions,selection of protective agent and rehydration activation conditions were the factors affecting the quality of the finished product.Therefore,rate and time,centrifugal dehydration of glucose content,activation temperature and time were changed.It was found that the best centrifugal condition was 4500 r/min and 10 min,the best protective agent is lactose,the dilution with water is 1:25,dehydration dehydration glucose content was 5%,the dehydration temperature of 45 ℃,time of rehydration and activation was 30 min.The prepared active dry yeast and fresh yeast was used in the fermentation experiment,and components at the end of fermentation were analyzed.The results indicated that under the same conditions,the residual sugar content and alcohol content from the fermentation of dry yeast and fresh yeast were close at the end of fermentation,suggesting that active dry yeast instead of fresh yeast in the very high gravity fermentation of ethanol was feasible.